viii PREFACE TO THE SECOND EDITION example, in submitting specimens of new or rare preparations, or in presenting an account of some small investigation. The present edition is much enlarged and contains new pre- parations, reactions and quantitative methods, all of which have been carefully revised. My object has been not to follow any particular syllabus, but to present a variety of processes from which a selection "may be made to suit the special needs of different students. My thanks are due to Mr. Joseph Marshall, B.Sc., and several of my senior students, for their assistance in the work of revision. J. B. COHEN THE UNIVERSITY, LEEDS. July, 1908.